Non-Invasive Assessment of Vascular Circulation Based on Flow Mediated Skin Fluorescence (FMSF)

Abstract

Flow Mediated Skin Fluorescence (FMSF) is a new non-invasive method for assessing vascular circulation and/or metabolic regulation. It enables assessment of both vasoconstriction and vasodilation. The method measures stimulation of the circulation in response to post-occlusive reactive hyperemia (PORH). It analyzes the dynamical changes in the emission of NADH fluorescence from skin tissue, providing the information on mitochondrial metabolic status and intracellular oxygen delivery through the circulatory system. Assessment of the vascular state using the FMSF technique is based on three parameters: reactive hyperemia response (RHR), hypoxia sensitivity (HS), and normoxia oscillatory index (NOI). The RHR and HS parameters determine the risk of vascular circulatory disorders and are the main diagnostic parameters. The NOI parameter is an auxiliary parameter for evaluating the state of microcirculation under stress of various origins (e.g., emotional stress, physical exhaustion, or post-infection stress). The clinical data show that the risk of vascular complications is limited among people whose RHR, log(HS), and NOI parameters are not significantly below the mean values determined by the FMSF technique, especially if they simultaneously meet the conditions RHR > 30% and log(HS) > 1.5 (HS > 30), and NOI > 60%.

A New Approach to Vascular Screening: Identification of Impaired Vascular Function Using the FMSF Technique

“…AngioExpert is a diagnostic tool based on the FMSF technique, produced by Angionica Ltd. (Lodz, Poland). The measurement protocol has been described in detail elsewhere [ 12 , 17 ]. Figure 2 shows an exemplary FMSF trace, consisting of three parts: the baseline, the ischemic response (IR), and the hyperemic (reperfusion) response (HR).…”

“…RHR is a unique parameter based on the combined responses from both the ischemic and hyperemic parts of the measured FMSF trace (RHR = IR max + HR max ). It represents the overall function of the vascular system, including both macro- and microcirculation [ 14 , 17 ]. The HS parameter represents a direct measure of the intensity of microcirculatory oscillations related to myogenic oscillations with frequencies in the range of 0.052–0.15 Hz, recorded during reperfusion [ 13 , 14 , 17 ].…”

“…It represents the overall function of the vascular system, including both macro- and microcirculation [ 14 , 17 ]. The HS parameter represents a direct measure of the intensity of microcirculatory oscillations related to myogenic oscillations with frequencies in the range of 0.052–0.15 Hz, recorded during reperfusion [ 13 , 14 , 17 ]. Myogenic microcirculatory oscillations are a very sensitive measure of the microcirculatory response to hypoxia and can be monitored with high precision using the FMSF technique.…”

“…For emotional stress, physical exhaustion, or post-infection stress, the NOI parameters have values below 60%. In the case of hormonal deficiency frequently associated with erectile dysfunction, the NOI parameter values are in the range of 90–100% [ 15 , 17 ].…”

“…In light of this, there is growing demand for a diagnostic tool that is both simple and non-invasive, for assessment of the body’s reaction to transient hypoxia. Addressing this need is the Flow Mediated Skin Fluorescence (FMSF) technique [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. The FMSF technique stands out for its ability to provide information on distinguishable macro- and microcirculatory responses to transient hypoxia.…”